/Engine/Source/Runtime/Experimental/GeometryCollectionEngine/Public/GeometryCollection/GeometryCollectionEngineConversion.h
static void AppendGeometryCollectionInstancedMeshes ( const [UGeometryCollection](API\Runtime\GeometryCollectionEngine\GeometryCollection\UGeometryCollection) * SourceGeometryCollectionObject, [UGeometryCollection](API\Runtime\GeometryCollectionEngine\GeometryCollection\UGeometryCollection) * TargetGeometryCollectionObject, int32 TargetTransformStartIndex )